Powertrain for eco-friendly vehicle

ABSTRACT

A powertrain for a vehicle includes an engine, a first motor serving as a motor for driving of a vehicle or serving as a generator, a first power transmission mechanism disposed between the engine and the first motor to transmit the power of the engine to the first motor or to cut off transmission of power between the engine and the first motor, a second power transmission mechanism disposed between the first motor and a driving shaft of running wheels to transmit the power of the first motor to the driving shaft of the running wheels or to cut off transmission of power between the first motor and the driving shaft of the running wheels, and a second motor connected to the second power transmission mechanism via a third power transmission mechanism to transmit power to the second power transmission mechanism and outputting power for driving the vehicle and transmit the power to the driving shaft of the running wheels.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of priorityto Korean Patent Application No. 10-2015-0102449 filed on Jul. 20, 2015,the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a powertrain for an eco-friendlyvehicle. More particularly, the present disclosure relates to a novelpowertrain for an eco-friendly vehicle which constitutes a rangeextender electric vehicle (EV) system including two motors and an enginesuch that power of the two motors are concurrently used as a runningpower for the vehicle.

BACKGROUND

A range extender electric vehicle (EV) technology has been developed asone of the technologies applicable to eco-friendly vehicles such aselectric vehicles. In the range extender electric vehicle technology, afirst motor for an engine and a generator is mounted on the vehicle inaddition to a second motor for the vehicle. Therefore, when a state ofcharge (SOC) of a battery falls below a threshold level, an engineoutput drives the first motor which is for a generator to charge thebattery while the vehicle runs by the second motor (running in a seriesmode), thereby increasing a running distance of the vehicle.

A conventional range extender EV technology will now be brieflydescribed with reference to FIG. 20.

Charge Depletion (CD) Mode

In a charge depletion mode in which a second motor MG2 drives a vehiclewhile consuming the electric power of the battery, only the second motorMG2 drives the vehicle, while the first motor MG1 for an engine and agenerator does not operate.

When a required power for the second motor MG2 for driving the vehicleis, for example, set to 125 kW, the second motor MG2 for driving thevehicle produces an output of 125 kW.

Charge Sustaining (CS) Mode

When the SOC of the battery falls below a threshold level while drivingusing the second motor MG2, the first motor MG1 for an engine and agenerator is driven by the output of the engine, and the second motorMG2 for driving the vehicle exerts an output of 20 kW while the firstmotor MG1 generates electric power and charges the battery.Consequently, the second motor MG2 cannot contribute to driving of thevehicle using the remaining power of about 100 kW (that is, theremaining power of about 100 kW is not employed).

As a result, in the conventional range extender EV technology, excessivepower for the second motor are applied, thereby increasing manufacturingcosts.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention, andtherefore, it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE DISCLOSURE

The present disclosure has been made in an effort to solve theabove-described problems associated with the prior art, and it is anobject of the present disclosure to provide a powertrain for aneco-friendly vehicle having a range extender EV system which includestwo motors and an engine such that an output of a first motor forelectrical generation in addition to an output of a second motor fordriving the vehicle are transmitted to running wheels while driving in acharge depletion mode to employ the outputs of the two motors as a powerfor driving the vehicle, thereby ensuring an output of the vehicle andreducing the required power for the second motor.

According to an exemplary embodiment, a powertrain for an eco-friendlyvehicle includes an engine, a first motor for operating as a motor fordriving a vehicle or for operating as a driving source for a generatorusing the power of the engine transmitted thereto, a first powertransmission mechanism disposed between the engine and the first motorso as to transmit the power of the engine to the first motor or to cutoff transmission of power between the engine and the first motor, asecond power transmission mechanism disposed between the first motor anda driving shaft of running wheels so as to transmit the power of thefirst motor to the driving shaft of the running wheels or to cut off thetransmission of power between the first motor and the driving shaft ofthe running wheels, and a second motor connected to the second powertransmission mechanism via a third power transmission mechanism totransmit power to the second power transmission mechanism, andoutputting power for driving the vehicle and transmits the power to thedriving shaft of the running wheels through the third power transmissionmechanism and the second power transmission mechanism.

According to another exemplary embodiment, a powertrain for aneco-friendly vehicle includes an engine, a first motor operating as amotor for driving a vehicle, a first power transmission mechanismdisposed between the engine and the first motor so as to transmit thepower of the engine to the first motor or to cut off transmission ofpower between the engine and the first motor, a second powertransmission mechanism disposed between the first motor and a drivingshaft of first running wheels to transmit the power of the first motorto the driving shaft of the first running wheels or to engage ordisengage transmission of power between the first motor and the drivingshaft of the first running wheels, and a second motor connected tosecond running wheels to transmit power to the second running wheels.

Other aspects and exemplary embodiments of the invention are discussedinfra.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g. fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

The above and other features of the invention are discussed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure will now bedescribed in detail with reference to certain exemplary embodimentsthereof illustrated the accompanying drawings which are givenhereinbelow by way of illustration only, and thus are not limitative ofthe present disclosure.

FIG. 1 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a first embodiment.

FIG. 2 illustrates the flow of power transmission in a first chargedepletion (1st CD) mode of the powertrain according to the firstembodiment.

FIG. 3 illustrates the flow of power transmission in a second chargedepletion (2nd CD) mode of the powertrain according to the firstembodiment.

FIG. 4 illustrates the flow of power transmission in a charge sustaining(CS) mode of the powertrain according to the first embodiment.

FIG. 5 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a second embodiment.

FIG. 6 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a third embodiment.

FIG. 7 illustrates the flow of power transmission in a first chargedepletion (1st CD) mode of the powertrain according to the thirdembodiment;

FIG. 8 illustrates the flow of power transmission in a second chargedepletion (2nd CD) mode of the powertrain according to the thirdembodiment.

FIG. 9 illustrates the flow of power transmission in a charge sustaining(CS) mode of the powertrain according to the third embodiment.

FIG. 10 shows the flow of power transmission in a parallel mode of thepowertrain according to the third embodiment.

FIG. 11 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a fourth embodiment.

FIG. 12 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a fifth embodiment.

FIG. 13 illustrates the flow of power transmission in a first chargedepletion (1st CD) mode of the powertrain according to the fifthembodiment.

FIG. 14 illustrates the flow of power transmission in a second chargedepletion (2nd CD) mode of the powertrain according to the fifthembodiment.

FIG. 15 illustrates the flow of power transmission in a chargesustaining (CS) mode of the powertrain according to the fifthembodiment.

FIG. 16 illustrates the flow of power transmission in a first parallelmode of the powertrain according to the fifth embodiment.

FIG. 17 illustrates the flow of power transmission in a second parallelmode of the powertrain according to the fifth embodiment.

FIG. 18 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a sixth embodiment.

FIG. 19 is a conceptual diagram illustrating that required power for thesecond motor can be reduced according to a powertrain for aneco-friendly vehicle according to the present disclosure.

FIG. 20 is a conceptual diagram illustrating a conventional rangeextender EV technology.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present disclosure throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodimentsof the present inventive concept, examples of which are illustrated inthe accompanying drawings and described below. While the invention willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention to those exemplary embodiments. On the contrary, the inventionis intended to cover not only the exemplary embodiments, but alsovarious alternatives, modifications, equivalents, and other embodiments,which may be included within the spirit and scope of the invention asdefined by the appended claims.

Hereinafter, exemplary embodiments will be described in detail withreference to the attached drawings so as to enable the embodiments to beeasily understood by one of ordinary skill in the art to which thisinvention belongs.

First Embodiment

FIG. 1 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a first embodiment.

The first embodiment provides a powertrain including an engine 10 andtwo motors, that is, a first motor MG1 and a second motor MG2. Theengine 10 provides only power for the generation of electrical powerrequired for charging a battery (not shown), which is the energy storagedevice for the vehicle.

The first motor MG1 is driven as a generator using power transmittedfrom the engine so as to charge a battery (charging by motor), oroperates as a vehicular driving source to supplement the output of thesecond motor MG2 (driving as motor).

The second motor MG2 is the motor for driving a vehicle, that is, foroutputting power required for running the vehicle, and the power outputfrom the second motor MG2 is ultimately transmitted to running wheels.

According to the first embodiment, the engine 10 is connected to thefirst motor MG1 so as to transmit its power to the first motor MG1. Thesecond motor MG2 is connected to the path, along which the power of thefirst motor MG1 is applied to the running wheels, so as to transmit itspower to the path.

A first power transmission mechanism is disposed between the engine 10and the first motor MG1 so as to transmit the power of the engine 10 tothe first motor MG1. Upon the operation of the first power transmissionmechanism, power of the first power transmission mechanism istransmitted to a first motor MG1.

The first power transmission mechanism includes: an engine gear 11coupled to the output shaft of the engine 10; a first intermediate gear13 coupled to a first power transmission shaft 12 and engaged with theengine gear 11; a second intermediate gear 14 coupled to the first powertransmission shaft 12 as being coaxial with the first intermediate gear13; and a first synchronizer 16 connected to the rotating shaft 15 ofthe first motor MG1. A first motor power transmission gear 17 isconnected to the rotating shaft 15 of the first motor MG1 via the firstsynchronizer 16 so as to selectively engage or disengage thetransmission of power between the first motor power transmission gear 17and the rotating shaft 15 of the first motor MG1 through the firstsynchronizer 16. The first motor power transmission gear 17 is engagedwith the second intermediate gear 14.

The first motor power transmission gear 17, which is coupled to therotating shaft 15 of the first motor MG1 in an idling manner, isintegrated with the rotating shaft 15 of the first motor MG1, therebyenabling transmission of power therebetween when the first synchronizer16 is closed.

When the first synchronizer 16 is closed, the power of the engine 10 istransmitted to the first motor MG1 through the engine gear 11, the firstintermediate gear 13, the first power transmission shaft 12, the secondintermediate gear 14, the first motor power transmission gear 17, thefirst synchronizer 16 and the rotating shaft 15 of the first motor MG1,thereby driving for electrical generation by the first motor MG1.

The first synchronizer 16, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first motor power transmission gear 17,engages or disengages the transmission of power between the rotatingshaft 15 of the first motor MG1 and the first motor power transmissiongear 17. The first synchronizer 16 may include a general clutch.

Since the first synchronizer 16 and all of the synchronizers applied tothe embodiments are well-known configurations, which engage or disengagetransmission of power between components disposed at both ends thereofor synchronizes the components at both ends with each other so as toenable the transmission of power therebetween upon closing of thesynchronizers, a detailed description thereof is omitted.

In the powertrain according to the present disclosure, closing andopening of the respective synchronizers is controlled in response tocontrol signals from a control unit of a vehicle, for example, atransmission control unit (TCU).

A second power transmission mechanism is disposed between the firstmotor MG1 and the rotating shaft 26 of the running wheels so as totransmit the power of the first motor MG1 to the driving shaft 26 of therunning wheels. Upon operation of the second power transmissionmechanism, the power of the first motor MG1 is transmitted to therunning wheels.

The second power transmission mechanism includes: a second synchronizer18 connected to the rotating shaft 15 of the first motor MG1; a firstoutput gear 19 connected to the rotating shaft 15 of the first motor MG1via the second synchronizer 18 so as to selectively engage or disengagethe transmission of power between the first output gear 19 and therotating shaft 15 of the first motor MG1 through the second synchronizer18; a second output gear 24 coupled to a second power transmission shaft23 and engaged with the first output gear 19; and a third output gear 25coupled to the second power transmission shaft 23 in the state of beingcoaxial with the second output gear 24 and connected to the drivingshaft 26 of the running wheels so as to enable the transmission of powerto the driving shaft 26 of the running wheels.

The second synchronizer 18, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first output gear 19, selectively engagesor disengages the transmission of power between the rotating shaft 15 ofthe first motor MG1 and the first output gear 19, and may include ageneral clutch.

The first output gear 19 is coupled to the rotating shaft 15 of thefirst motor MG1 in the idling manner. Upon closing of the secondsynchronizer 18, the rotating shaft 15 of the first motor MG1 isintegrated with the first output gear 19, thereby enabling thetransmission of power therebetween.

When the second synchronizer 18 is closed, the power of the first motorMG1 is transmitted to the driving shaft 26 of the running wheels throughthe rotating shaft 15 of the first motor MG1, the second synchronizer18, the first output gear 19, the second output gear 24, the secondpower transmission shaft 23 and the third output gear 25.

The power transmitted from the first motor MG1 may be used as anauxiliary power required for driving the vehicle. That is, the power maysupplement the power transmitted to the driving shaft 26 of the runningwheels from the second motor MG2 to assist the driving of the vehicle.

According to the first embodiment, the rotating shaft 20 of the secondmotor MG2 is connected to the second power transmission mechanism via athird power transmission mechanism so as to transmit power to the secondpower transmission mechanism such that the rotating shaft 20 of thesecond motor MG2 transmits power to the running wheels, either incooperation with or independently of the first motor MG1.

The third power transmission mechanism includes: a first transmissiongear 21 coupled to the rotating shaft 20 of the second motor MG2; and asecond transmission gear 22 coupled to the second power transmissionshaft 23 of the second power transmission mechanism and engaged with thefirst transmission gear 21. The second transmission gear 22 is furtherconnected to the third output gear 25 of the second power transmissionmechanism in the state of being coaxial with the third output gear 25.

Accordingly, the power of the second motor MG2 is transmitted to thedriving shaft 26 of the running wheels through the rotating shaft 20,the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23 and the third output gear 25.

The power transmitted from the second motor MG2 is used as a runningpower required for driving the vehicle.

In summary, the powertrain according to the first embodiment includesthree parallel shafts, that is, the first power transmission shaft 12,the rotating shaft 15 of the first motor MG1 and the second powertransmission shaft 23, and further includes two synchronizers to engageor disengage the transmission of power, that are, the first synchronizer16 and the second synchronizer 18.

The first synchronizer 16 serves as an engine clutch adapted to engageor disengage the transmission of power between the engine 10 and thefirst motor MG1. The second synchronizer 18 engages or disengages thetransmission of power to the running wheels from the first motor MG1such that the power of the first motor MG1 and the power of the secondmotor MG2 are concurrently used as the running power for the vehicle(the power required for driving the vehicle).

In the double motor driving mode, the second power transmission shaft 23serves as a final power transmission shaft which receives both the powerof the first motor MG1 and the power of the second motor MG2 andtransmits the combined force to the driving shaft 26 of the runningwheels through the third output gear 25.

The running wheels may be either front or rear pair of wheels. The firstembodiment shown in FIG. 1 illustrates a two wheel drive (2WD)construction, which employs the running wheels (front wheels or rearwheels) as the driving wheels.

Operational states and flows of power transmission in variousoperational modes of the powertrain according to the first embodiment,which is constructed as described above, will now be described.

First Charge Depletion Mode

FIG. 2 illustrates a flow of power transmission in a first chargedepletion (1st CD) mode of the powertrain according to the firstembodiment.

The first charge depletion mode is an electric vehicle (EV) running modein which the second motor MG2, which is the driving motor of thevehicle, operates by consuming the battery power. Thus, the vehicle runsby the power of the second motor MG2 when the SOC of the battery is at areference value or higher. Here, the vehicle runs by operation only ofthe second motor MG2 without operation of the engine 10 and the firstmotor MG1 for electrical generation (single motor driving).

Accordingly, in the first charge depletion mode, only the power of thesecond motor MG2 is transmitted to the driving shaft 26 of the runningwheels through the third power transmission mechanism, the second powertransmission shaft 23 of the second power transmission mechanism and thethird output gear 25 of the second power transmission mechanism withoutthe transmission of power through the first power transmission mechanismand the second power transmission mechanism.

In the first charge depletion mode, both synchronizers 16 and 18 areopened, that is, both the first synchronizer 16 of the first powertransmission mechanism and the second synchronizer 18 of the secondpower transmission mechanism are opened. Accordingly, the transmissionof power between the engine 10 and the first motor MG1 is disengaged,and the transmission of power between the rotating shaft 15 of the firstmotor MG1 and the second power transmission shaft 23 is disengaged. Onlythe power of the second motor MG2 is transmitted to the driving shaft 26of the running wheels through the third power transmission mechanism,the second power transmission shaft 23 of the second power transmissionmechanism, and the third output gear 25 of the second power transmissionmechanism.

Here, the power of the second motor MG2 is ultimately transmitted to thedriving shaft 26 of the running wheels through the rotating shaft 20,the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23, and the third output gear 25.

Second Charge Depletion Mode

FIG. 3 illustrates a flow of power transmission in a second chargedepletion (2nd CD) mode of the powertrain according to the firstembodiment.

The second charge depletion mode is an electric vehicle (EV) runningmode in which the second motor MG2, which is the main driving motor of avehicle, and the first motor MG1, which is the auxiliary driving motor,operate by consuming the power of the battery. Thus, the vehicle runs bythe power of the second motor MG2 and the first motor MG1 when the SOCof the battery is at a reference value (which is equal to or differentfrom the reference value in the first charge depletion mode) or higher.Here, the vehicle runs by the transmission of the power of the secondmotor MG2 to the running wheels and the transmission of the power of thefirst motor MG1 to the running wheels without the operation of theengine 10 (double motor driving).

Accordingly, in the second charge depletion mode, the power of thesecond motor MG2 is transmitted to the driving shaft 26 of the runningwheels through the third power transmission mechanism and the secondpower transmission mechanism (the second power transmission shaft andthe third output gear) while the power of the first motor MG1 istransmitted to the driving shaft 26 of the running wheels through thesecond power transmission mechanism under the condition that thetransmission of power through the first power transmission mechanism isblocked while the transmission of power through the second powertransmission mechanism is allowed.

More specifically, the second charge depletion mode is implemented insuch a manner that the power of the second motor MG2 is transmitted tothe driving shaft 26 of the running wheels through the third powertransmission mechanism and the power of the first motor MG1 istransmitted to the driving shaft 26 of the running wheels through thesecond power transmission mechanism by closing the second synchronizer18 of the second power transmission mechanism.

The power of the second motor MG2 is ultimately transmitted to thedriving shaft 26 of the running wheels through the rotating shaft 20,the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23 and the third output gear 25.

At the same time, the power of the first motor MG1 is transmitted to thedriving shaft 26 of the running wheels through the rotating shaft 15,the second synchronizer 18, the first output gear 19, the second outputgear 24, the second power transmission shaft 23 and the third outputgear 25 by closing the second synchronizer 18.

In the second charge depletion mode, the first synchronizer 16 of thefirst power transmission mechanism is controlled to be opened.

In the second charge depletion mode according to the first embodiment,the output (23.5 kW) of the first motor MG1 is added to the output(101.5 kW) of the second motor MG2, thus producing the total output of125 kW, as shown in FIG. 19.

Therefore, even if the required power for the second motor MG2 ischanged to 101.5 kW from 125 kW, it is possible to ensure the totaloutput of 125 kW by power assistance from the first motor MG1, and it ispossible to lower manufacturing costs by reducing the required power forthe second motor MG2.

Charge Sustaining Mode

FIG. 4 illustrates a flow of power transmission in a charge sustaining(CS) mode of the powertrain according to the first embodiment.

The charge sustaining mode is a series running mode in which, when theSOC of the battery falls below the reference value while the secondmotor MG2 serves as the main driving motor of the vehicle, the firstmotor MG1 operates as a driving source of the generator by the power ofthe engine 10 and the second motor MG2 operates by the electric power ofthe battery which is accumulated by the first motor MG1, therebyproducing a desired output (for example, 20 kW).

Accordingly, in the charge sustaining mode, the power of the secondmotor MG2 is transmitted to the driving shaft 26 of the running wheelsthrough the third power transmission mechanism, the second powertransmission shaft 23 and the third output gear 25 while the power ofthe engine 10 is transmitted to the first motor MG1 through the firstpower transmission mechanism under the condition that the transmissionof power through the first power transmission mechanism is allowed whilethe transmission of power through the second power transmissionmechanism is blocked, thereby operating the first motor MG1 as a drivingsource of the generator.

More specifically, the power of the second motor MG2 is transmitted tothe driving shaft 26 of the running wheels through the third powertransmission mechanism, and the transmission of power between the firstmotor MG1 and the second power transmission shaft 23 is disengaged byopening the second synchronizer 18 of the second power transmissionmechanism.

At the same time, the power of the engine 10 is transmitted to the firstmotor MG1 through the engine gear 11, the first intermediate gear 13,the first power transmission shaft 12, the second intermediate gear 14,the first motor power transmission gear 17, the first synchronizer 16and the rotating shaft 15 of the first motor MG1 by closing the firstsynchronizer 16 of the first power transmission mechanism, therebyoperating the first motor MG1 as the driving source of a generator.

When the SOC of the battery falls below the predetermined value, thefirst motor MG1 operates by the power of the engine 10, thereby chargingthe battery. At this time, the output of the second motor MG2 iscontrolled to be decreased.

In the charge sustaining mode of the powertrain according to the firstembodiment of the present invention, the output of the second motor MG2is decreased (for example, to 20 kW) and is applied to the runningwheels, as shown in FIG. 19. Accordingly, even if the required power forthe second motor MG2 is decreased to 101.5 kW from 125 kW, there is noproblem at all in producing an output of 20 kW. Therefore, the secondmotor MG2 having a lowered power can be applied, and manufacturing costscan be reduced by virtue of the reduced power for the second motor MG2.

Second Embodiment

FIG. 5 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a second embodiment of the presentinvention.

Unlike the first embodiment, which is the powertrain for a 2WD vehicle,the second embodiment is a powertrain for a four-wheel-drive (4WD)vehicle.

In a second charge depletion mode, when the power of the first motorMG1, which is a running power required for driving a vehicle, istransmitted to the driving shaft 26, if the running wheels which aredriven by the power of the first motor MG1 are the rear wheels, thepower of the second motor MG2 is transmitted to the front wheels througha decelerator 30, and accordingly all of the front wheels and the rearwheels can be used as driving wheels.

In certain embodiments, the running wheels to which the power of thefirst motor MG1 is transmitted may be the front wheels, and the runningwheels to which the power of the second motor MG2 is transmitted may bethe rear wheels.

In the 4WD operation, the rotating shaft 20 of the second motor MG2 isconnected to the driving shaft 31 of the running wheels through thedecelerator 30, as shown in FIG. 5.

Referring to FIG. 5, the second motor MG2 is not connected to the engine10 and the first motor MG1, but is connected to the driving shaft 31corresponding to the other running wheels so as to transmit power to thedriving shaft 31.

The second embodiment also employs the second motor MG2 as the maindriving source for running a vehicle. Accordingly, in the first chargedepletion mode, the second motor MG2 operates, and the power of thesecond motor MG2 is transmitted to the driving shaft 31 of the runningwheels through the decelerator 30, thereby driving the vehicle.

As shown in FIG. 5, there is no difference between the first embodimentand the second embodiment except that the second motor MG2 is connectedto the other running wheels to which the first motor MG1 is notconnected so as to transmit power. The third power transmissionmechanism, which includes the first transmission gear 21 and the secondtransmission gear 22, is excluded because the rotating shaft 20 of thesecond motor MG2 is not connected to the second power transmission shaft23 in a power transmittable manner.

That is, the engine 10 is connected to the first motor MG1 so as totransmit the power required only to charge the battery (not shown).

The first motor MG1 is driven as a generator using power transmittedfrom the engine (charging by motor), or operates as a vehicular drivingsource to supplement the output of the second motor MG2 (driving asmotor).

The first power transmission mechanism for transmitting the power of theengine 10 to the first motor MG1 is disposed between the engine 10 andthe first motor MG1. By the operation of the first power transmissionmechanism, the power of the engine 10 is transmitted to the first motorMG1.

The first power transmission mechanism includes: an engine gear 11coupled to the engine 10; a first intermediate gear 13 coupled to afirst power transmission shaft 12 and engaged with the engine gear 11; asecond intermediate gear 14 coupled to the first power transmissionshaft 12 which is coaxial with the first intermediate gear 13; and afirst synchronizer 16 connected to the rotating shaft 15 of the firstmotor MG1. A first motor power transmission gear 17 is connected to therotating shaft 15 of the first motor MG1 via the first synchronizer 16such that the transmission of power between the rotating shaft 15 of thefirst motor MG1 and the first motor power transmission gear 17 isselectively engaged or disengaged by the first synchronizer 16. Thefirst motor power transmission gear 17 is engaged with the secondintermediate gear 14.

The first motor power transmission gear 17 is coupled to the rotatingshaft 15 of the first motor MG1 in an idling manner. Upon closing of thefirst synchronizer 16, the rotating shaft 15 of the first motor MG1 isintegrated with the first motor power transmission gear 17, therebyenabling the transmission of power therebetween.

Upon closing of the first synchronizer 16, the power of the engine 10 istransmitted to the first motor MG1 through the engine gear 11, the firstintermediate gear 13, the first power transmission shaft 12, the secondintermediate gear 14, the first motor power transmission gear 17, thefirst synchronizer 16, and the rotating shaft 15 of the first motor MG1,thereby operating the first motor MG1 as a driving source for electricalgeneration.

The first synchronizer 16, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first motor power transmission gear 17,selectively engages or disengages the transmission of power between therotating shaft 15 of the first motor MG1 and the first motor powertransmission gear 17, and may include a general Clutch.

The second power transmission mechanism for transmitting the power ofthe first motor MG1 to the driving shaft 26 of the running wheels isdisposed between the first motor MG1 and the driving shaft 26 of therunning wheels. By the operation of the second power transmissionmechanism, the power of the first motor MG1 is transmitted to therunning wheels.

The second power transmission mechanism includes: a second synchronizer18 connected to the rotating shaft 15 of the first motor MG1; a firstoutput gear 19 connected to the rotating shaft 15 of the first motor MG1via the second synchronizer 18 such that the transmission of powerbetween the first output gear 19 and the rotating shaft 15 of the firstmotor MG1 is selectively engaged or disengaged by the secondsynchronizer 18; a second output gear 24 coupled to the second powertransmission shaft 23 and engaged with the first output gear 19; and athird output gear 25 coupled to the second power transmission shaft 23to be coaxial with the second output gear 24 and connected to thedriving shaft 26 of the running wheels so as to transmit the power tothe driving shaft 26 of the running wheels.

The second synchronizer 18, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first output gear 19, selectively engagesor disengages the transmission of power between the rotating shaft 15 ofthe first motor MG1 and the first output gear 19, and may include ageneral clutch.

The first output gear 19 is coupled to the rotating shaft 15 of thefirst motor MG1 in the idling manner. Upon closing of the secondsynchronizer 18, the rotating shaft 15 of the first motor MG1 isintegrated with the first output gear 19, thereby enabling thetransmission of power therebetween.

When the second synchronizer 18 is closed, the power of the first motorMG1 is transmitted to the driving shaft 26 of the running wheels throughthe rotating shaft 15 of the first motor MG1, the second synchronizer18, the first output gear 19, the second output gear 24, the secondpower transmission shaft 23, and the third output gear 25.

The power, which is transmitted from the first motor MG1 in this way,may be used as auxiliary power required for running the vehicle. Thatis, the power may supplement the power transmitted to the driving shaft31 of the other running wheels, which are not connected to the drivingshaft 26, through the decelerator 30 from the second motor MG2 to assistin driving the vehicle. The power of the second motor MG2 is used as themain power required for driving the vehicle.

The operational states and flows of power transmission in variousoperational modes of the powertrain according to the second embodiment,which is constructed as describe above, will now be described.

First Charge Depletion Mode

With the exception that the power of the second motor MG2 is transmittedto the driving shaft 31 of the running wheels through the decelerator30, there is no difference between the first embodiment and the secondembodiment in operational states, other components, or flows of powertransmission.

The first charge depletion mode is an electric vehicle (EV) running modein which the second motor MG2, which is the driving motor of a vehicle,operates by consuming battery power. Thus, the vehicle runs by the powerof second motor MG2 when the SOC of the battery is at a reference valueor higher and in which the vehicle runs by operation of only the secondmotor MG2 without operation of the engine 10 and operation of the firstmotor MG1 for electrical generation (single motor driving).

Accordingly, the first charge depletion mode is implemented in such amanner that only the power of the second motor MG2 is ultimatelytransmitted to the driving shaft 31 of the running wheels through thedecelerator 30 without the transmission of power through the first powertransmission mechanism and the second power transmission mechanism.

In the first charge depletion mode, both synchronizers 16 and 18 areopened, that is, both the first synchronizer 16 of the first powertransmission mechanism and the second synchronizer 18 of the secondpower transmission mechanism are opened. Accordingly, the transmissionof power between the engine 10 and the first motor MG1 is disengaged,and the transmission of power between the rotating shaft 15 of the firstmotor MG1 and the second power transmission shaft 23 is disengaged. Onlythe power of the second motor MG2 is transmitted to the driving shaft 31of the running wheels through the decelerator 30.

Second Charge Depletion Mode

The power of the second motor MG2 is transmitted to the driving shaft 31of the running wheels through the decelerator 30, however, there is nodifference between the first embodiment and the second embodiment inoperational states, other components, or flows of power transmission.

The second charge depletion mode is an electric vehicle (EV) runningmode in which the second motor MG2, which is the main driving motor of avehicle, and the first motor MG1, which is the auxiliary driving motor,operate by consuming the power of the battery. Thus, the vehicle runs bythe power of the second motor MG2 and the first motor MG1 when the SOCof the battery is at a reference value (which is equal to or differentfrom the reference value in the first charge depletion mode) or higherand in which the vehicle runs by the transmission of the power of thesecond motor MG2 to the running wheels and the transmission of the powerof the first motor MG1 to the running wheels without the operation ofthe engine 10 (double motor driving).

Since both the power of the first motor MG1 and the power of the secondmotor MG2 are transmitted to the rear wheels and the front wheels,respectively, 4WD operation, in which both the rear and front wheels aredriven, is implemented.

Accordingly, in the second charge depletion mode, the power of thesecond motor MG2 is transmitted to the driving shaft 31 of the runningwheels through the decelerator 30 while the power of the first motor MG1is transmitted to the driving shaft 26 of the running wheels through thesecond power transmission mechanism under the condition that thetransmission of power through the first power transmission mechanism isblocked while the transmission of power through the second powertransmission mechanism is allowed.

More specifically, the second charge depletion mode is implemented insuch a manner that the power of the second motor MG2 is transmitted tothe driving shaft 31 of the running wheels through the accelerator 30.The power of the first motor MG1 is transmitted to the driving shaft 26of the running wheels through the second power transmission mechanism byclosing the second synchronizer 18 of the second power transmissionmechanism.

Here, the power of the first motor MG1 is transmitted to the drivingshaft 26 of the running wheels through the rotating shaft 15, the secondsynchronizer 18, the first output gear 19, the second output gear 24,the second power transmission shaft 23, and the third output gear 25 byclosing the second synchronizer 18.

In the second charge depletion mode, the first synchronizer 16 of thefirst power transmission mechanism is controlled to be opened.

Charge Sustaining Mode

The power of the second motor MG2 is transmitted to the driving shaft 31of the running wheels through the decelerator 30, however, there is nodifference between the first embodiment and the second embodiment inoperational states, other components or flows of power transmission.

The charge sustaining mode is a series running mode in which, when theSOC of the battery falls below the reference value while the secondmotor MG2 serves as the main driving motor of the vehicle, the firstmotor MG1 operates as a driving source of the generator by the power ofthe engine 10 and the second motor MG2 operates by the electric power ofthe battery which is accumulated by the first motor MG1, therebyproducing a desired output (for example, 20 kW).

Accordingly, in the charge sustaining mode, the power of the secondmotor MG2 is transmitted to the driving shaft 31 of the running wheelsthrough the decelerator 30 while the power of the engine 10 istransmitted to the first motor MG1 through the first power transmissionmechanism under the condition that the transmission of power through thefirst power transmission mechanism is allowed while the transmission ofpower through the second power transmission mechanism is blocked,thereby operating the first motor MG1 as the driving source of thegenerator.

That is, the power of the second motor MG2 is transmitted to the drivingshaft 31 of the running wheels through the decelerator 30, and the powertransmission between the first motor MG1 and the second powertransmission shaft 23 is disengaged by opening the second synchronizer18 of the second power transmission mechanism.

At the same time, the power of the engine 10 is transmitted to the firstmotor MG1 through the engine gear 11, the first intermediate gear 13,the first power transmission shaft 12, the second intermediate gear 14,the first motor power transmission gear 17, the first synchronizer 16and the rotating shaft 15 of the first motor MG1 by closing the firstsynchronizer 16 of the first power transmission mechanism, therebycausing the first motor MG1 to operate as the driving source of agenerator.

When the SOC of the battery falls below the predetermined value, thefirst motor MG1 operates by the power of the engine 10, thereby chargingthe battery. At this time, the output of the second motor MG2 isdecreased.

Third Embodiment

FIG. 6 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a third embodiment.

The third embodiment provides a powertrain including an engine 10 andtwo motors, that is, a first motor MG1 and a second motor MG2. Theengine 10 provides power only for the generation of electrical powerrequired for charging a battery (not shown), which is the energy storagedevice for the vehicle, or supplements the output of the second motorMG2 so as to serve as a driving source for running the vehicle.

In the third embodiment, the power of the engine 10 may supplement thepower of the second motor MG2. Here, the power of the engine 10 isdivided into the power for electrical generation and the power requiredfor driving the running wheels, and is used for both the electricalgeneration and the running of the vehicle.

The first motor MG1 is driven as a generator using the power transmittedfrom the engine so as to charge a battery (charging by motor), oroperates as a vehicular driving source to supplement the output of thesecond motor MG2 (driving as motor).

The second motor MG2 is the motor serving as a main driving source fordriving the vehicle, that is, for outputting the power required fordriving the vehicle, and the power output from the second motor MG2 isultimately transmitted to the running wheels.

The powertrain according to the third embodiment further includes afourth power transmission mechanism, which is disposed between the firstpower transmission mechanism and the second power transmission mechanismso as to selectively transmit the remaining power divided from theengine 10 (not the power for electrical generation) to the second powertransmission mechanism, which is connected to the running wheels fromthe first power transmission mechanism.

The fourth power transmission mechanism includes a third synchronizer 42selectively transmitting the power divided from the engine 10 (not thepower for electrical generation) some of the power of the engine 10 fordriving the vehicle, which is separated from the remaining power of theengine 10 for electrical generation, to the second power transmissionshaft 23 of the second power transmission mechanism from the first powertransmission mechanism. The third synchronizer 42 is connected to thesecond power transmission shaft 23. The fourth power transmissionmechanism further includes a fourth output gear 41 connected to thesecond power transmission shaft 23 via the third synchronizer 42 suchthat the transmission of power between the fourth output gear 41 and thesecond power transmission shaft 23 is selectively engaged or disengagedby the third synchronizer 42. The fourth output gear 41 is engaged withthe first motor power transmission gear 17.

The fourth output gear 41 is coupled to the second power transmissionshaft 23 in an idling manner. When the third synchronizer 42 is closed,the fourth output gear 41 is integrated with the second powertransmission shaft 23, thereby allowing the transmission of powertherethrough.

When the first synchronizer 16 and the third synchronizer 42 are closed,the power divided from the engine 10 (not the power for electricalgeneration), which is transmitted to the first motor MG1 through thefirst power transmission mechanism, is ultimately transmitted to thedriving shaft 26 of the running wheels through the first motor powertransmission gear 17, the fourth output gear 41, the third synchronizer42, the second power transmission shaft 23 and the third output gear 25.

Except the further provision of the fourth power transmission mechanism,the other constructions are equal to those of the first embodiment. Thatis, the third embodiment further includes the fourth power transmissionmechanism in addition to the construction of the first embodiment.

Specifically, the engine 10 is connected to the first motor MG1 totransmit the power to the first motor MG1, and the second motor MG2 isconnected to the path, through which the power of the first motor MG1 isapplied to the running wheels, to transmit the power to the runningwheels.

The first power transmission mechanism is disposed between the engine 10and the first motor MG1 so as to transmit the power of the engine 10 tothe first motor MG1. Upon the operation of the first power transmissionmechanism, the power of the engine 10 is transmitted to the first motorMG1.

The first power transmission mechanism includes an engine gear 11coupled to the output shaft of the engine 10; a first intermediate gear13 is coupled to a first power transmission shaft 12 and engaged withthe engine gear 11; a second intermediate gear 14 coupled to the firstpower transmission shaft 12 coaxial with the first intermediate gear 13;and a first synchronizer 16 connected to the rotating shaft 15 of thefirst motor MG1. A first motor power transmission gear 17 is connectedto the rotating shaft 15 of the first motor MG1 via the firstsynchronizer 16 such that the transmission of power between the firstmotor power transmission gear 17 and the rotating shaft 15 of the firstmotor MG1 is selectively engaged or disengaged by the first synchronizer16. The first motor power transmission gear 17 is engaged with thesecond intermediate gear 14.

The first motor power transmission gear 17 is coupled to the rotatingshaft 15 of the first motor MG1 in the idling manner. Upon closing ofthe first synchronizer 16, the rotating shaft 15 of the first motor MG1is integrated with the first motor power transmission gear 17, therebyenabling the transmission of power therebetween.

Upon closing of the first synchronizer 16, the power of the engine 10 istransmitted to the first motor MG1 through the engine gear 11, the firstintermediate gear 13, the first power transmission shaft 12, the secondintermediate gear 14, the first motor power transmission gear 17, thefirst synchronizer 16 and the rotating shaft 15 of the first motor MG1,thereby operating the first motor MG1 as a driving source for electricalgeneration.

The first synchronizer 16, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first motor power transmission gear 17,selectively engages or disengages the transmission of power between therotating shaft 15 of the first motor MG1 and the first motor powertransmission gear 17, and may include a general clutch.

The second power transmission mechanism for transmitting the power ofthe first motor MG1 to the driving shaft 26 of the running wheels isdisposed between the first motor MG1 and the driving shaft 26 of therunning wheels. By the operation of the second power transmissionmechanism, the power of the first motor MG1 is transmitted to therunning wheels.

The second power transmission mechanism includes: a second synchronizer18 connected to the rotating shaft 15 of the first motor MG1; and afirst output gear 19 connected to the rotating shaft 15 of the firstmotor MG1 via the second synchronizer 18 such that the transmission ofpower between the first output gear 19 and the rotating shaft 15 of thefirst motor MG1 is selectively engaged or disengaged by the secondsynchronizer 18. A second output gear 24 is coupled to the second powertransmission shaft 23 and engaged with the first output gear 19. A thirdoutput gear 25 is coupled to the second power transmission shaft 23,which is coaxial with the second output gear 24, and connected to thedriving shaft 26 of the running wheels so as to transmit the power tothe driving shaft 26 of the running wheels.

The second synchronizer 18, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first output gear 19, selectively engagesor disengages the transmission of power between the rotating shaft 15 ofthe first motor MG1 and the first output gear 19, and may include ageneral clutch.

The first output gear 19 is coupled to the rotating shaft 15 of thefirst motor MG1 in the idling manner. Upon closing of the secondsynchronizer 18, the rotating shaft 15 of the first motor MG1 isintegrated with the first output gear 19, thereby enabling thetransmission of power therebetween.

When the second synchronizer 18 is closed, the power of the first motorMG1 is transmitted to the driving shaft 26 of the running wheels throughthe rotating shaft 15 of the first motor MG1, the second synchronizer18, the first output gear 19, the second output gear 24, the secondpower transmission shaft 23, and the third output gear 25.

The power transmitted from the first motor MG1 may be used as auxiliarypower required for running the vehicle. That is, the power maysupplement the power transmitted to the driving shaft 26 of the runningwheels from the second motor MG2 so as to assist in driving the vehicle.

According to the third embodiment, the rotating shaft 20 of the secondmotor MG2 is connected to the second power transmission mechanism viathe third power transmission mechanism so as to transmit the power tothe second power transmission mechanism such that the second motor MG2transmits the power to the running wheels, either in conjunction with orindependently of the first motor MG1.

The third power transmission mechanism includes a first transmissiongear 21 coupled to the rotating shaft 20 of the second motor MG2 and asecond transmission gear 22, which is coupled to the second powertransmission shaft 23 of the second power transmission mechanism so asto engage with the first transmission gear 21. The first transmissiongear 21 is coaxially connected to the third output gear 25 of the secondpower transmission mechanism.

Accordingly, the power of the second motor MG2 is ultimately transmittedto the driving shaft 26 of the running wheels through the rotating shaft20, the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23, and the third output gear 25.

The power of the second motor MG2, which is transmitted in this way, isused as the running power required for driving the vehicle.

In summary, the third embodiment includes three parallel shafts, namely,the first power transmission shaft 12, the rotating shaft 15 of thefirst motor MG1 and the second power transmission shaft 23, and furtherincludes a total of three synchronizers for engaging or disengaging thetransmission of power, that are, the first synchronizer 16, the secondsynchronizer 18, and the third synchronizer 42.

The first synchronizer 16 serves as an engine clutch adapted to engageor disengage the transmission of power between the engine 10 and thefirst motor MG1. The second synchronizer 18 serves to engage ordisengage the transmission of power to the running wheels from the firstmotor MG1 such that the double motor driving is performed, that is, thepower of the first motor MG1 and the power of the second motor MG2 areconcurrently used as the running power for the vehicle (the powerrequired for driving the vehicle).

In the double motor driving mode, the second power transmission shaft 23serves as a final power transmission shaft and receives both the powerof the first motor MG1 and the power of the second motor MG2 andtransmits the combined force to the driving shaft 26 of the runningwheels through the third output gear 25.

The third synchronizer 42 engages or disengages the transmission of theremaining power which is divided from the engine 10 (not the power forelectrical generation transmitted to the first motor MG1) andtransmitted to the running wheels.

Due to the further provision of the third synchronizer 42, parallel modeoperation may be implemented in such a way that some of the power of theengine 10 supplements the output of the second motor MG2. Thus, some ofthe power of the engine 10 and the power of the second motor MG2 areused together to drive the vehicle.

The running wheels may be one pair of wheels selected from among thefront wheels and the rear wheels. The third embodiment in FIG. 6illustrates a two-wheel-drive (2WD) construction in which all of thepower of the engine, the power of the first motor MG1 and the power ofthe second motor MG2 are transmitted to the running wheels (front wheelsor rear wheels) and the running wheels are used as the driving wheels.

In the powertrain according to the third embodiment, the vehicle can runin one of the first charge depletion mode, the second charge depletionmode, the charge sustaining mode, and the parallel mode.

Among these modes, since the first charge depletion mode, the secondcharge depletion mode, and the charge sustaining mode do not havefeatures that distinguish them from the first embodiment in terms of theoperational states of the components and the flows of powertransmission, as shown in FIGS. 7 to 9, a detailed description thereofis omitted.

The operational states and flows of power transmission in the parallelmode, which are additionally realized by the provision of the fourthpower transmission mechanism, will now be described.

Parallel Mode

FIG. 10 shows a flow of power transmission in a parallel mode of thepowertrain according to the third embodiment.

The parallel mode is a running mode of the vehicle in which some of thepower of the engine 10 supplements the output of the second motor MG2such that both some of the power of the engine 10 and the power of thesecond motor MG2 are used to drive the vehicle.

In the parallel mode, the power of the engine 10 is divided into thepower for electrical generation and the power for driving the runningwheels so as to be used both in the electrical generation and thedriving of the vehicle. Here, the first motor MG1 operates as a drivingsource for the generator using the divided power of the engine 10 tocharge the battery.

Here, the power of the second motor MG2 is transmitted to the drivingshaft 26 of the running wheels through the third power transmissionmechanism and the second power transmission shaft 23 of the second powertransmission mechanism.

At this time, the power of the second motor MG2 is transmitted to thedriving shaft 26 of the running wheels through the rotating shaft 20,the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23 and the third output gear 25.

Some of the power of the engine 10 is transmitted to the first motor MG1so as to be used as the power for electrical generation, and theremaining power of the engine 10 is transmitted to the driving shaft 26of the running wheels through the fourth power transmission mechanismand the second power transmission shaft 23 of the second powertransmission mechanism so as to be used as an auxiliary power fordriving the vehicle. The first synchronizer 16 and the thirdsynchronizer 42 are controlled to be closed whereas the secondsynchronizer 18 is controlled to be opened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16 and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the third synchronizer 42 is closed, the remaining power dividedfrom the engine 10 (not the power transmitted to the first motor MG1 forelectrical generation) is ultimately transmitted to the driving shaft 26of the running wheels through the first motor power transmission gear17, the fourth output gear 41, the third synchronizer 42, the secondpower transmission shaft 23 and the third output gear 25.

Fourth Embodiment

FIG. 11 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a fourth embodiment.

While the third embodiment is a 2WD powertrain for a vehicle, the fourthembodiment is a 4WD powertrain for a vehicle, as in the secondembodiment.

In a second charge depletion mode, when the power of the first motorMG1, which is running power required to run the vehicle, is transmittedto the driving shaft 26 of the running wheels, if the running wheelswhich are driven by the power of the first motor MG1 are the rearwheels, the power of the second motor MG2 is transmitted to the frontwheels through a decelerator 30. Accordingly, all of the front wheelsand the rear wheels can be used as driving wheels.

On the other hand, the running wheels to which the power of the firstmotor MG1 is transmitted may be the front wheels, and the running wheelsto which the power of the second motor MG2 is transmitted may be therear wheels.

For the purpose of implementing 4WD operation, the rotating shaft 20 ofthe second motor MG2 is connected to a driving shaft 31 of the runningwheels through the decelerator 30, as shown in FIG. 11.

Referring to FIG. 11, the second motor MG2 is not connected to theengine 10 and to the first motor MG1, but is connected to the drivingshaft 31 of the other running wheels, which are not connected to thedriving shaft 26, so as to transmit power to the driving shaft 31.

The fourth embodiment also employs the second motor MG2 as the maindriving source for running the vehicle. Accordingly, in the first chargedepletion mode, the second motor MG2 operates, and the power of thesecond motor MG2 is transmitted to the driving shaft 31 of the runningwheels through the decelerator 30, thereby running the vehicle.

As shown in FIG. 11, the third embodiment and the fourth embodiment aresimilar except that the second motor MG2 is connected to the otherrunning wheels, which are not connected to the first motor MG1, throughthe decelerator 30 so as to transmit power and that the third powertransmission mechanism, which includes the first transmission gear 21and the second transmission gear 22, is excluded because the rotatingshaft 20 of the second motor MG2 is not connected to the second powertransmission shaft 23 in a power transmittable manner.

Similar to the third embodiment, the fourth embodiment includes theparallel mode, compared to the first embodiment and the secondembodiment. The power of the second motor MG2 for driving a vehicle ineach of the first charge depletion mode, the second charge depletionmode, the charge sustaining mode, and the parallel mode is transmittedto the driving shaft 31 of the running wheels through the decelerator30.

Although the power of the second motor MG2 is transmitted to the drivingshaft 31 of the running wheels through the decelerator 30, there is nodifference between the fourth embodiment and the third embodiment in theoperational states of other components or flows of power transmission,and thus, only the parallel mode will be described, in order to avoidredundant descriptions.

Parallel Mode

The parallel mode is a running mode of a vehicle in which some of thepower of the engine 10 supplements the output of the second motor MG2such that some of the power of the engine 10 and the power of the secondmotor MG2 are used together to drive the vehicle.

In the parallel mode, the power of the engine 10 is divided into thepower for electrical generation and the power for driving the runningwheels so as to be used both in the electrical generation and thedriving of the vehicle. Here, the first motor MG1 operates as a drivingsource for the generator using the some of the power of the engine 10 tocharge the battery.

In the parallel mode, the power of the second motor MG2 is ultimatelytransmitted to the driving shaft 31 of the other running wheels, whichare not connected to the driving shaft 26, through the decelerator 30.

In the parallel mode, some of the power of the engine 10 is transmittedto the first motor MG1 so as to be used as the power for electricalgeneration, and the remaining power of the engine 10 is transmitted tothe driving shaft 26 of the running wheels through the fourth powertransmission mechanism and the second power transmission shaft 23 of thesecond power transmission mechanism so as to be used as the auxiliarypower for driving the vehicle. To this end, the first synchronizer 16and the third synchronizer 42 are closed, whereas the secondsynchronizer 18 is opened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16, and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the third synchronizer 42 is closed, the remaining power dividedfrom the engine 10 (not the power transmitted to the first motor MG1 forelectrical generation) is ultimately transmitted to the driving shaft 26of the running wheels through the first motor power transmission gear17, the fourth output gear 41, the third synchronizer 42, the secondpower transmission shaft 23 and the third output gear 25.

Fifth Embodiment

FIG. 12 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a fifth embodiment.

The fifth embodiment provides a powertrain including an engine 10 andtwo motors, which are, a first motor MG1 and a second motor MG2. Theengine 10 provides power only for the generation of electrical powerrequired to charge a battery (not shown), which is a energy storagedevice for the vehicle, or supplements the output of the second motorMG2 so as to serve as the driving source for running the vehicle.

When the power of the engine 10 is used to supplement the output of thesecond motor MG2, the power of the engine is divided into the power forelectrical generation and the power for driving the running wheels to beused both in the electrical generation and the driving of the vehicle.

The first motor MG1 is driven as a generator using power transmittedfrom the engine 10 (charging by motor), or operates as a vehiculardriving source to supplement the output of the second motor MG2 (drivingas motor).

The second motor MG2 is the motor serving as the main driving source fordriving a vehicle, that is, for outputting the power required forrunning the vehicle, and the power output from the second motor MG2 isultimately transmitted to running wheels.

The powertrain according to the fifth embodiment has features thatdistinguish it from the third embodiment in that two paths, throughwhich the remaining power divided from the engine 10 (not the power forelectrical generation) is transmitted to the running wheels, areprovided such that the divided power is ultimately transmitted to therunning wheels through one selected from the two paths.

Accordingly, there are two parallel modes, which drive a vehicle throughthe divided power of the engine 10 and the power of the second motor MG2through the two paths. Here, the two paths through which the dividedpower is transmitted have different gear ratios.

The powertrain according to the fifth embodiment further includes afourth synchronizer 43 engaging or disengaging the transmission of powerbetween the second output gear 24 and the second power transmissionshaft 23, in addition to the components of the third embodiment.

The fourth synchronizer 43 is connected to the second power transmissionshaft 23.

The second output gear 24 is connected to the second power transmissionshaft 23 via the fourth synchronizer 43 and engaged with the firstoutput gear 19, so that the transmission of power between the secondoutput gear 24 and the second power transmission shaft 23 is selectivelyengaged or disengaged by the fourth synchronizer 43.

The second output gear 24 is coupled to the second power transmissionshaft 23 in an idling manner. Upon closing of the fourth synchronizer43, the second power transmission shaft 23 is integrated with the secondoutput gear 24, thereby allowing the transmission of power therebetween.

Accordingly, there is no difference between the fifth embodiment and thethird embodiment, with the exception that the transmission of powerbetween the second output gear 24 and the second power transmissionshaft 23 is engaged or disengaged by closing or opening of the fourthsynchronizer 43.

Specifically, in the construction of the powertrain according to thefifth embodiment, the first power transmission mechanism is disposedbetween the engine 10 and the first motor MG1 so as to transmit thepower of the engine 10 to the first motor MG1. Upon the operation of thefirst power transmission mechanism, the power of the engine 10 istransmitted to the first motor MG1.

The first power transmission mechanism includes: an engine gear 11coupled to the output shaft of the engine 10; a first intermediate gear13 coupled to a first power transmission shaft 12 and engaged with theengine gear 11; and a second intermediate gear 14 coupled to the firstpower transmission shaft 12, which is coaxial with the firstintermediate gear 13. A first synchronizer 16 is connected to therotating shaft 15 of the first motor MG1. A first motor powertransmission gear 17 is connected to the rotating shaft 15 of the firstmotor MG1 via the first synchronizer 16 such that transmission of powerbetween the first motor power transmission gear 17 and the rotatingshaft 15 of the first motor MG1 is selectively engaged or disengaged bythe first synchronizer 16, and engaged with the second intermediate gear14.

The first motor power transmission gear 17 is coupled to the rotatingshaft 15 of the first motor MG1 in the idling manner. Upon closing ofthe first synchronizer 16, the rotating shaft 15 of the first motor MG1is integrated with the first motor power transmission gear 17, therebyenabling the transmission of power therebetween.

Upon closing of the first synchronizer 16, the power of the engine 10 istransmitted to the first motor MG1 through the engine gear 11, the firstintermediate gear 13, the first power transmission shaft 12, the secondintermediate gear 14, the first motor power transmission gear 17, thefirst synchronizer 16 and the rotating shaft 15 of the first motor MG1,thereby causing the first motor MG1 to operate as a driving source forelectrical generation.

The first synchronizer 16, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first motor power transmission gear 17,selectively engages or disengages the transmission of power between therotating shaft 15 of the first motor MG1 and the first motor powertransmission gear 17, and may include a general clutch.

The second power transmission mechanism for transmitting the power ofthe first motor MG1 to the driving shaft 26 of the running wheels isdisposed between the first motor MG1 and the driving shaft 26 of therunning wheels. By the operation of the second power transmissionmechanism, the power of the first motor MG1 is transmitted to therunning wheels.

The second power transmission mechanism includes: a second synchronizer18 connected to the rotating shaft 15 of the first motor MG1; a firstoutput gear 19 connected to the rotating shaft 15 of the first motor MG1via the second synchronizer 18 such that the transmission of powerbetween the first output gear 19 and the rotating shaft 15 of the firstmotor MG1 is selectively engaged or disengaged by the secondsynchronizer 18; and a second output gear 24 coupled to the second powertransmission shaft 23 and engaged with the first output gear 19. A thirdoutput gear 25 is coupled to the second power transmission shaft 23,which is coaxial with the second output gear 24 and is connected to thedriving shaft 26 of the running wheels so as to transmit the power tothe driving shaft 26 of the running wheels.

The second synchronizer 18, which synchronizes the rotating shaft 15 ofthe first motor MG1 with the first output gear 19, selectively engagesor disengages the transmission of power between the rotating shaft 15 ofthe first motor MG1 and the first output gear 19, and may include ageneral clutch.

The first output gear 19 is coupled to the rotating shaft 15 of thefirst motor MG1 in the idling manner. Upon closing of the secondsynchronizer 18, the rotating shaft 15 of the first motor MG1 isintegrated with the first output gear 19, thereby enabling thetransmission of power therebetween.

Accordingly, when the second synchronizer 18 is closed, the power of thefirst motor MG1 is transmitted to the driving shaft 26 of the runningwheels through the rotating shaft 15 of the first motor MG1, the secondsynchronizer 18, the first output gear 19, the second output gear 24,the second power transmission shaft 23, and the third output gear 25.

The power, which is transmitted from the first motor MG1 in this way,may be used as an auxiliary power required for running a vehicle. Thatis, the power may supplement the power transmitted to the driving shaft26 of the running wheels from the second motor MG2 so as to assist indriving a vehicle.

According to the fifth embodiment, the rotating shaft 20 of the secondmotor MG2 is connected to the second power transmission mechanism viathe third power transmission mechanism so as to transmit the power tothe second power transmission mechanism such that the second motor MG2transmits the power to the running wheels, either in conjunction with orindependently of the first motor MG1.

The third power transmission mechanism includes a first transmissiongear 21 coupled to the rotating shaft 20 of the second motor MG2 and asecond transmission gear 22, which is coupled to the second powertransmission shaft 23 of the second power transmission mechanism so asto engage with the first transmission gear 21. The first transmissiongear 21 is coaxially connected to the third output gear 25 of the secondpower transmission mechanism.

Accordingly, the power of the second motor MG2 is ultimately transmittedto the driving shaft 26 of the running wheels through the rotating shaft20, the first transmission gear 21, the second transmission gear 22, thesecond power transmission shaft 23, and the third output gear 25.

The power of the second motor MG2, which is transmitted in this way, isused as the running power required for driving the vehicle.

The running wheels may be any pair of wheels selected from among thefront and rear pairs of wheels. The fifth embodiment shown in FIG. 12illustrates a two-wheel-drive (2WD) construction that employs therunning wheels (front wheels or rear wheels) as the driving wheels.

The powertrain according to the fifth embodiment further includes afourth power transmission mechanism, which is disposed between the firstpower transmission mechanism and the second power transmission mechanismso as to selectively transmit the remaining power divided from theengine 10 (not the power for electrical generation) to the second powertransmission mechanism which is connected to the running wheels from thefirst power transmission mechanism.

The fourth power transmission mechanism includes a third synchronizer 42selectively transmitting the remaining power divided from the engine 10(not the power for electrical generation) to the second powertransmission shaft 23 of the second power transmission mechanism fromthe first power transmission mechanism. The third synchronizer 42 isconnected to the second power transmission shaft 23. The fourth powertransmission mechanism further includes a fourth output gear 41connected to the second power transmission shaft 23 via the thirdsynchronizer 42 such that the transmission of power between the fourthoutput gear 41 and the second power transmission shaft 23 is selectivelyengaged or disengaged by the third synchronizer 42. The fourth outputgear 41 is engaged with the first motor power transmission gear 17.

The fourth output gear 41 is coupled to the second power transmission 23in an idling manner. When the third synchronizer 42 is closed, thefourth output gear 41 is integrated with the second power transmissionshaft 23, thereby allowing the transmission of power therethrough.

When the first synchronizer 16 and the third synchronizer 42 are closed,the remaining power divided from the engine 10 (not the powertransmitted to the first motor MG1 from the first power transmissionmechanism for electrical generation) is ultimately transmitted to thedriving shaft 26 of the running wheels through the first motor powertransmission gear 17, the fourth output gear 41, the third synchronizer42, the second power transmission shaft 23, and the third output gear25.

According to the fifth embodiment of FIG. 12, the powertrain includesthe first power transmission shaft 12, the rotating shaft 15 of thefirst motor MG1, and the second power transmission shaft 23, and furtherincludes the first synchronizer 16, the second synchronizer 18, and thethird synchronizer 42.

The first synchronizer 16 serves as an engine clutch adapted to engageor disengage the transmission of power between the engine 10 and thefirst motor MG1. The second synchronizer 18 engages or disengages thetransmission of power to the running wheels from the first motor MG1such that the power of the first motor MG1 and the power of the secondmotor MG2 are concurrently used as the running power for a vehicle (thepower required for driving the vehicle).

In the double motor driving mode, the second power transmission shaft 23serves as a final power transmission shaft, which receives both thepower of the first motor MG1 and the power of the second motor MG2 andtransmits the combined force to the driving shaft 26 of the runningwheels through the third output gear 25.

The third synchronizer 42 engages or disengages the transmission of theremaining power which is divided from the engine 10 and transmitted tothe running wheels (not the power transmitted to the first motor MG1 forelectrical generation).

In the parallel mode operation, some of the power of the engine 10supplements the power of the second motor MG2 such that both some of thepower of the engine 10 and the power of the second motor MG2 are used todrive the vehicle.

According to the fifth embodiment, there are two power transmissionpaths, through which the remaining power which is divided from theengine 10 and transmitted to the running wheels (not the power forelectrical generation), more specifically, the two power transmissionpaths through which the power divided from the engine 10 is transmittedto the second power transmission shaft 23 from the rotating shaft 15 ofthe first motor MG1. Therefore, either of the two parallel modes mayoperate depending on a change in a transmission path. One of the twopower transmission paths includes the first output gear 19 and thesecond output gear 24 engaging with the first output gear 19, and theother includes the first motor power transmission gear 17 and the fourthoutput gear 41 engaging with the first motor power transmission gear 17.In order to have different gear ratios in the two power transmissionpaths, the gear ratio of the second output gear 24 to the first outputgear 19 is controlled to be different from the gear ratio of the fourthoutput gear 41 to the first motor power transmission gear 17.

In the powertrain according to the fifth embodiment, the vehicle can runin one of the first charge depletion mode, the second charge depletionmode, the charge sustaining mode, the first parallel mode, and thesecond parallel mode.

Among these modes, since the first charge depletion mode, the secondcharge depletion mode and the charge sustaining mode do not havefeatures that distinguish them from the first embodiment and the thirdembodiment in terms of the operational states of the components and theflows of power transmission, as shown in FIGS. 13 to 15, a detaileddescription thereof is omitted.

Specifically, the first parallel mode does not have features thatdistinguish it from the parallel mode in the third embodiment in termsof the operational states of the components and the flows of powertransmission, as shown in FIG. 16. The operational states and flows ofpower transmission in the first parallel mode and the second parallelmode will now be described.

FIG. 16 illustrates the flow of power transmission of the powertrainaccording to the fifth embodiment in the first parallel mode. FIG. 17shows the flow of power transmission of the powertrain according to thefifth embodiment in the second parallel mode.

Each of the first parallel mode and the second parallel mode is arunning mode of a vehicle in which some of the power of the engine 10supplements the power of the second motor MG2 such that both some of thepower of the engine 10 and the power of the second motor MG2 are used todrive the vehicle.

In the first and second parallel modes, the power of the engine 10 isdivided into the power for electrical generation and the power fordriving the running wheels so as to be used both in the electricalgeneration and the driving of the vehicle. Here, the first motor MG1operates as the driving source for the generator using the some of thepower of the engine 10 to charge the battery.

In the first and second parallel modes, the power of the second motorMG2 is ultimately transmitted to the running wheels through the thirdpower transmission mechanism and the second power transmission shaft 23of the second power transmission mechanism.

More specifically, in the first and second parallel modes, the power ofthe second motor MG2 is transmitted to the driving shaft 26 of therunning wheels through the rotating shaft 20, the first transmissiongear 21, the second transmission gear 22, the second power transmissionshaft 23 and the third output gear 25.

First Parallel Mode

In the first parallel mode, during the transmission of power of thefirst power transmission mechanism for transmitting the power of theengine 10 to the first motor MG1, the disengagement of the transmissionof power between the first motor MG1 and the driving shaft 26 of therunning wheels by the second power transmission mechanism or thetransmission of power by the fourth power transmission mechanism, theremaining power divided from the engine 10 (not the power transmitted tothe first motor MG1 for electrical generation) is transmitted to thedriving shaft 26 of the running wheels through the first powertransmission mechanism, the fourth power transmission mechanism and thesecond power transmission mechanism so as to be used together with thepower of the second motor MG2 to drive the vehicle.

The first parallel mode is described in more detail with reference toFIG. 16. Some of the power of the engine 10 is transmitted to the firstmotor MG1 so as to be used as the power for electrical generation, andthe remaining power of the engine 10 is transmitted to the driving shaft26 of the running wheels through the fourth power transmission mechanismand the second power transmission shaft 23 of the second powertransmission mechanism so as to be used as the auxiliary power fordriving the vehicle. Here, the first synchronizer 16 and the thirdsynchronizer 42 are closed, whereas the second synchronizer 18 and thefourth synchronizer 43 are opened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16, and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the third synchronizer 42 is closed, the remaining power dividedfrom the engine 10 (not the power transmitted to the first motor MG1 forelectrical generation) is ultimately transmitted to the driving shaft 26of the running wheels through the first motor power transmission gear17, the fourth output gear 41, the third synchronizer 42, the secondpower transmission shaft 23 and the third output gear 25.

Second Parallel Mode

In the second parallel mode, during the transmission of power of thefirst power transmission mechanism for transmitting the power of theengine 10 to the first motor MG1, the engagement of the transmission ofpower between the rotating shaft 15 of the first motor MG1 and thedriving shaft 26 of the running wheels by the second power transmissionmechanism, the disengagement of the transmission of power by the fourthpower transmission mechanism, and the transmission of power by thefourth synchronizer 43, the remaining power divided from the engine 10(not the power transmitted to the first motor MG 1 for electricalgeneration) is transmitted to the driving shaft 26 of the running wheelsthrough the first power transmission mechanism, the fourth synchronizer43 and the second power transmission mechanism so as to be used togetherwith the power of the second motor MG2 to drive the vehicle.

The second parallel mode is described in more detail with reference toFIG. 17. Some of the power of the engine 10 is transmitted to the firstmotor MG1 so as to be used as the power for electrical generation, andthe remaining power of the engine 10 is transmitted to the driving shaft26 of the running wheels through the fourth synchronizer 43 and thesecond power transmission shaft 23 of the second power transmissionmechanism so as to be used as the auxiliary power for driving thevehicle. The first synchronizer 16, the second synchronizer 18, and thefourth synchronizer 43 are closed, whereas the third synchronizer 42 isopened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16, and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the second synchronizer 18 and the fourth synchronizer 43 areclosed, the remaining power divided from the engine 10 (not the powertransmitted to the first motor MG 1 for electrical generation) isultimately transmitted to the driving shaft 26 of the running wheelsthrough the rotating shaft 15 of the first motor MG1, the secondsynchronizer 18, the first output gear 19, the second output gear 24,the fourth synchronizer 43, the second power transmission shaft 23, andthe third output gear 25.

Sixth Embodiment

FIG. 18 is a power transmission system diagram showing a powertrain foran eco-friendly vehicle according to a sixth embodiment.

While the fifth embodiment is a 2WD powertrain for a vehicle, the sixthembodiment is a 4WD powertrain for a vehicle, as in the secondembodiment and the fourth embodiment.

In a second charge depletion mode, when the power of the first motorMG1, which is running power required for driving a vehicle istransmitted to the driving shaft 26 of the running wheels, if therunning wheels which are driven by the power of the first motor MG1 arethe rear wheels, the power of the second motor MG2 is transmitted to thefront wheels through a decelerator 30. Accordingly, all of the frontwheels and the rear wheels can be used as driving wheels.

In some embodiments, the running wheels to which the power of the firstmotor MG1 is transmitted may be the front wheels, and the running wheelsto which the power of the second motor MG2 is transmitted may be therear wheels.

For the purpose of implementing 4WD operation, the rotating shaft 20 ofthe second motor MG2 is connected to a driving shaft 31 of the runningwheels through the decelerator 30, as shown in FIG. 18.

Referring to FIG. 18, the second motor MG2 is not connected to theengine 10 and the first motor MG1, but is connected to the driving shaft31 of the other running wheels, which are not connected to the drivingshaft 26, so as to transmit power to the driving shaft 31.

The sixth embodiment employs the second motor MG2 as a main drivingsource for running the vehicle. Accordingly, in the first chargedepletion mode, the second motor MG2 operates, and the power of thesecond motor MG2 is transmitted to the driving shaft 31 of the runningwheels through the decelerator 30, thereby driving the vehicle.

As shown in FIG. 18, there is no difference between the fifth embodimentand the sixth embodiment except that the second motor MG2 is connectedto the other running wheels, which are not connected to the first motorMG1, is connected. The third power transmission mechanism, whichincludes the first transmission gear 21 and the second transmission gear22, is excluded because the rotating shaft 20 of the second motor MG2 isnot connected to the second power transmission shaft 23 in a powertransmittable manner.

Like the fifth embodiment, the sixth embodiment further includes thefirst and second parallel modes, compared to the first embodiment andthe second embodiment. The power of the second motor MG2 for driving avehicle in any one of the first charge depletion mode, the second chargedepletion mode, the charge sustaining mode, the first parallel mode, andthe second parallel mode is transmitted to the driving shaft 31 of therunning wheels through the decelerator 30.

With the exception that the power of the second motor MG2 is transmittedto the driving shaft 31 of the running wheels through the decelerator30, there is no difference between the sixth embodiment and the fifthembodiment in the operational states of other components and flows ofpower transmission, and thus, only the parallel mode will be describedin order to avoid redundant descriptions.

Specifically, the first parallel mode does not have features thatdistinguish it from the parallel mode in the third embodiment in termsof the operational states of the components and flows of powertransmission, as shown in FIG. 16. The operational states and flows ofpower transmission in the first parallel mode and the second parallelmode will now be described.

The first parallel mode and the second parallel mode are running modesof a vehicle in which some of the power of the engine 10 supplements thepower of the second motor MG2 such that both some of the power of theengine 10 and the power of the second motor MG2 are used to drive thevehicle.

In the first and second parallel modes, the power of the engine 10 isdivided into the power for electrical generation and the power fordriving the running wheels so as to be used both in the electricalgeneration and the driving of the vehicle. Here, the first motor MG1operates as the driving source for the generator using some of the powerof the engine 10 to charge the battery.

In the first and second parallel modes, the power of the second motorMG2 is ultimately transmitted to the running wheels through thedecelerator 30.

First Parallel Mode

The first parallel mode is a mode in which, during the transmission ofpower of the first power transmission mechanism for transmitting thepower of the engine 10 to the first motor MG1, the disengagement of thetransmission of power between the first motor MG1 and the driving shaft26 of the running wheels by the second power transmission mechanism andthe transmission of power by the fourth power transmission mechanism,the remaining power divided from the engine 10 (not the powertransmitted to the first motor MG1 for electrical generation) istransmitted to the driving shaft 26 of the running wheels through thefirst power transmission mechanism, the fourth power transmissionmechanism and the second power transmission mechanism so as to be usedtogether with the power of the second motor MG2 (which is transmitted tothe driving shaft corresponding to the other running wheels through thedecelerator) to drive the vehicle.

More specifically, some of the power of the engine 10 is transmitted tothe first motor MG1 so as to be used as the power for electricalgeneration, and the remaining power of the engine 10 is transmitted tothe driving shaft 26 of the running wheels through the fourth powertransmission mechanism and the second power transmission shaft 23 of thesecond power transmission mechanism so as to be used as the auxiliarypower for driving the vehicle. Here, the first synchronizer 16 and thethird synchronizer 42 are closed, whereas the second synchronizer 18 andthe fourth synchronizer 43 are opened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16 and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the third synchronizer 42 is closed, the remaining power dividedfrom the engine 10 (not the power transmitted to the first motor MG1 forelectrical generation) is ultimately transmitted to the driving shaft 26of the running wheels through the first motor power transmission gear17, the fourth output gear 41, the third synchronizer 42, the secondpower transmission shaft 23 and the third output gear 25.

Second Parallel Mode

In the second parallel mode, during the transmission of power of thefirst power transmission mechanism for transmitting the power of theengine 10 to the first motor MG1, engagement of the transmission ofpower is made between the rotating shaft 15 of the first motor MG1 andthe driving shaft 26 of the running wheels by the second powertransmission mechanism, and disengagement of the transmission of powerof the fourth power transmission mechanism and the transmission of powerof the fourth synchronizer 43 is made. Remaining power divided from theengine 10 (not the power transmitted to the first motor MG 1 forelectrical generation) is transmitted to the driving shaft 26 of therunning wheels through the first power transmission mechanism, thefourth synchronizer 43, and the second power transmission mechanism soas to be used together with the power of the second motor MG2 (which istransmitted to the driving shaft corresponding to the other runningwheels through the decelerator) to drive the vehicle.

More specifically, some of the power of the engine 10 is transmitted tothe first motor MG1 so as to be used as the power for electricalgeneration, and the remaining power of the engine 10 is transmitted tothe driving shaft 26 of the running wheels through the fourthsynchronizer 43 and the second power transmission shaft 23 of the secondpower transmission mechanism so as to be used as the auxiliary power fordriving the vehicle. Here, the first synchronizer 16, the secondsynchronizer 18 and the fourth synchronizer 43 are closed, whereas thethird synchronizer 42 is opened.

By closing the first synchronizer 16, some of the power of the engine 10is transmitted to the first motor MG1 through the engine gear 11, thefirst intermediate gear 13, the first power transmission shaft 12, thesecond intermediate gear 14, the first motor power transmission gear 17,the first synchronizer 16, and the rotating shaft 15 of the first motorMG1, and is then used in the electrical generation by the first motorMG1.

While the second synchronizer 18 and the fourth synchronizer 43 areclosed, the remaining power divided from the engine 10 (not the powertransmitted to the first motor MG 1 for electrical generation) isultimately transmitted to the driving shaft 26 of the running wheelsthrough the rotating shaft 15 of the first motor MG1, the secondsynchronizer 18, the first output gear 19, the second output gear 24,the fourth synchronizer 43, the second power transmission shaft 23, andthe third output gear 25.

As described above, the present disclosure offers the followingadvantages.

When a vehicle runs in a charge depletion mode in a state in which anSOC of the battery is at a reference value or higher, the power of thefirst motor in addition to the power of the second motor for driving thevehicle is transmitted to the running wheels, and accordingly therequired power for the second motor for driving the vehicle can bereduced, thereby reducing manufacturing costs.

Even though the required power for the second motor is reduced, thepower of the first motor for electrical generation in addition to thepower of the second motor for driving the vehicle is transmitted to therunning wheels. Accordingly, it is possible to maintain the total powerin the charge depletion mode at a desired level, set before the requiredpower for the second motor is reduced.

The invention has been described in detail with reference to exemplaryembodiments thereof. However, it will be appreciated by those skilled inthe art that changes may be made in these embodiments without departingfrom the principles and spirit of the invention, the scope of which isdefined in the appended claims and their equivalents.

What is claimed is:
 1. A powertrain for an eco-friendly vehiclecomprising: an engine; a first motor for driving of a vehicle orreceiving power from the engine to operate as a generator; a first powertransmission mechanism disposed between the engine and the first motorto transmit engine power to the first motor or to cut off the powertransmission between the engine and the first motor; a second powertransmission mechanism disposed between the first motor and a drivingshaft of running wheels to transmit power from the first motor to thedriving shaft of the running wheels or to cut off the power transmissionbetween the first motor and the driving shaft of the vehicle wheels; anda second motor connected to the second power transmission mechanism viaa third power transmission mechanism to transmit power to the secondpower transmission mechanism, the second motor outputting power fordriving the vehicle and transmitting power to the driving shaft of therunning wheels through the third power transmission mechanism and thesecond power transmission mechanism.
 2. The powertrain according toclaim 1, wherein the first power transmission mechanism comprises: anengine gear coupled to an output shaft of the engine; a firstintermediate gear coupled to a first power transmission shaft andengaged with the engine gear; a second intermediate gear coupled to thefirst power transmission shaft which is coaxial with the firstintermediate gear; a first synchronizer connected to a rotating shaft ofthe first motor; and a first motor power transmission gear connected tothe rotating shaft of the first motor via the first synchronizer suchthat transmission of power between the first motor power transmissiongear and the rotating shaft of the first motor is selectively engaged ordisengaged by the first synchronizer, the first motor power transmissiongear being engaged with the second intermediate gear.
 3. The powertrainaccording to claim 1, wherein the second power transmission mechanismcomprises: a second synchronizer connected to the rotating shaft of thefirst motor; a first output gear connected to the rotating shaft of thefirst motor via the second synchronizer such that transmission of powerbetween the first output gear and the rotating shaft of the first motoris selectively engaged or disengaged by the second synchronizer; asecond output gear coupled to a second power transmission shaft andengaged with the first output gear; and a third output gear coupled tothe second power transmission shaft that is coaxial with the secondoutput gear and connected to the driving shaft of the running wheels ina power transmittable manner.
 4. The powertrain according to claim 3,wherein the third power transmission mechanism comprises: a firsttransmission gear coupled to a rotating shaft of the second motor; and asecond transmission gear coupled to the second power transmission shaftto be axial with the third output gear and engaged with the firsttransmission gear.
 5. The powertrain according to claim 1, wherein afirst charge depletion mode is implemented in which only power of thesecond motor is transmitted to the driving shaft of the running wheelsthrough the third power transmission mechanism and the second powertransmission mechanism during disengagement of the power transmissionbetween the engine and the first motor by the first power transmissionmechanism and during disengagement of the power transmission between thefirst motor and the driving shaft of the running wheels by the secondpower transmission mechanism.
 6. The powertrain according to claim 1,wherein a second charge depletion mode is implemented in which power ofthe first motor is transmitted to the driving shaft of the runningwheels through the second power transmission mechanism and power of thesecond motor is transmitted to the driving shaft of the running wheelsthrough the third power transmission mechanism and the second powertransmission mechanism during disengagement of the power transmissionbetween the engine and the first motor by the first power transmissionmechanism and during the power transmission of the second powertransmission mechanism for transmitting power of the first motor to thedriving shaft of the running wheels.
 7. The powertrain according toclaim 1, wherein a charge sustaining mode is implemented in which powerof the engine is transmitted to the first motor through the first powertransmission mechanism for electrical generation and power of the secondmotor is transmitted to the driving shaft of the running wheels throughthe third power transmission mechanism and the second power transmissionmechanism during power transmission of the first power transmissionmechanism for transmitting power of the engine to the first motor andduring disengagement of transmission of power between the first motorand the driving shaft of the running wheels by the second powertransmission mechanism.
 8. The powertrain according to claim 1, furthercomprising a fourth power transmission mechanism, which is disposedbetween the first power transmission mechanism and the second powertransmission mechanism to selectively transmit the remaining powerdivided from the engine to the second power transmission mechanism,which is connected to the driving shaft of the running wheels, from thefirst power transmission mechanism.
 9. The powertrain according to claim8, wherein the fourth power transmission mechanism comprises: a thirdsynchronizer connected to the second power transmission shaft whichtransmits power to the driving shaft of the running wheels from thesecond power transmission mechanism; and a fourth output gear connectedto the second power transmission shaft via the third synchronizer suchthat transmission of power between the fourth output gear and the secondpower transmission shaft is selectively engaged or disengaged by thethird synchronizer, the fourth output gear being engaged with the firstmotor power transmission gear which transmits power of the engine fromthe first power transmission mechanism.
 10. The powertrain according toclaim 8, wherein a parallel mode is implemented in which the remainingpower divided from the engine is transmitted to the driving shaft of therunning wheels through the first power transmission mechanism, thefourth power transmission mechanism, and the second power transmissionmechanism to be used together with power of the second motor to drivethe vehicle during power transmission of the first power transmissionmechanism for transmitting power of the engine to the first motor andduring disengagement of transmission of power between the first motorand the driving shaft of the running wheels by the second powertransmission mechanism and power transmission of the fourth powertransmission mechanism.
 11. The powertrain according to claim 8, whereinthe second power transmission mechanism comprises: a second synchronizerconnected to a rotating shaft of the first motor; a first output gearconnected to the rotating shaft of the first motor via the secondsynchronizer such that transmission of power between the first outputgear and the rotating shaft of the first motor is selectively engaged ordisengaged by the second synchronizer; a second output gear coupled tothe second power transmission shaft and engaged with the first outputgear; and a third output gear coupled to the second power transmissionshaft, which is coaxial with the second output gear, and connected tothe driving shaft of the running wheels in a power transmittable manner,wherein the powertrain further comprises a fourth synchronizer connectedto the second power transmission shaft to engage or disengagetransmission of power between the second output gear and the secondpower transmission shaft.
 12. The powertrain according to claim 9,wherein the second power transmission mechanism comprises: a secondsynchronizer connected to a rotating shaft of the first motor; a firstoutput gear connected to the rotating shaft of the first motor via thesecond synchronizer such that transmission of power between the firstoutput gear and the rotating shaft of the first motor is selectivelyengaged or disengaged by the second synchronizer; a second output gearcoupled to the second power transmission shaft and engaged with thefirst output gear; and a third output gear coupled to the second powertransmission shaft, which is coaxial with the second output gear, andconnected to the driving shaft of the running wheels to transmit powerto the driving shaft of the running wheels, wherein the powertrainfurther comprises a fourth synchronizer connected to the second powertransmission shaft such that the power transmission between the secondoutput gear and the second power transmission shaft is engaged ordisengaged, and wherein a gear ratio of the second output gear to thefirst output gear is different from a gear ratio of the fourth outputgear to the first motor power transmission gear.
 13. The powertrainaccording to claim 11, wherein a parallel mode is implemented in whichthe remaining power divided from the engine is transmitted to thedriving shaft of the running wheels through the first power transmissionmechanism, the fourth synchronizer, and the second power transmissionmechanism to be used together with power of the second motor to drivethe vehicle during power transmission of the first power transmissionmechanism for transmitting power of the engine to the first motor,during the power transmission of the second power transmission mechanismfor engaging transmission of power between the rotating shaft of thefirst motor and the driving shaft of the running wheels, and duringdisengagement of power transmission of the fourth power transmissionmechanism and power transmission of the fourth synchronizer.
 14. Apowertrain for an eco-friendly vehicle comprising: an engine; a firstmotor for operating as a motor for vehicle driving; a first powertransmission mechanism disposed between the engine and the first motorto transmit power of the engine to the first motor or to cut off thepower transmission between the engine and the first motor; a secondpower transmission mechanism disposed between the first motor and adriving shaft of first running wheels to transmit power of the firstmotor to the driving shaft of the first running wheels or to cut off thepower transmission between the first motor and the driving shaft of thefirst running wheels; and a second motor connected to second runningwheels to transmit power to the second running wheels.
 15. Thepowertrain according to claim 14, wherein the first power transmissionmechanism comprises: an engine gear coupled to an output shaft of theengine; a first intermediate gear coupled to a first power transmissionshaft and engaged with the engine gear; a second intermediate gearcoupled to the first power transmission shaft, which is coaxial with thefirst intermediate gear; a first synchronizer connected to a rotatingshaft of the first motor; and a first motor power transmission gearconnected to the rotating shaft of the first motor via the firstsynchronizer such that transmission of power between the first motorpower transmission gear and the rotating shaft of the first motor isselectively engaged or disengaged by the first synchronizer, the firstmotor power transmission gear being engaged with the second intermediategear.
 16. The powertrain according to claim 14, wherein the second powertransmission mechanism comprises: a second synchronizer connected to therotating shaft of the first motor; a first output gear connected to therotating shaft of the first motor via the second synchronizer such thattransmission of power between the first output gear and the rotatingshaft of the first motor is selectively engaged or disengaged by thesecond synchronizer; a second output gear coupled to a second powertransmission shaft and engaged with the first output gear; and a thirdoutput gear coupled to the second power transmission shaft, which iscoaxial with the second output gear, and connected to the driving shaftof the first running wheels in a power transmittable manner.
 17. Thepowertrain according to claim 16, wherein when the first running wheelsare one of the front wheels and rear wheels of the vehicle, the secondrunning wheels are the other one, wherein the second motor is connectedto the driving shaft of the running wheels via a decelerator.
 18. Thepowertrain according to claim 14, wherein a first charge depletion modeis implemented in which only power of the second motor is transmitted tothe driving shaft of the second running wheels through a deceleratorduring disengagement of the power transmission between the engine andthe first motor by the first power transmission mechanism anddisengagement of the power transmission between the first motor and thedriving shaft of the first running wheels by the second powertransmission mechanism.
 19. The powertrain according to claim 14,wherein a second charge depletion mode is implemented in which power ofthe first motor is transmitted to the driving shaft of the first runningwheels through the second power transmission mechanism and power of thesecond motor is transmitted to the driving shaft of the second runningwheels through the decelerator during disengagement of transmission ofpower between the engine and the first motor by the first powertransmission mechanism and during power transmission of the second powertransmission mechanism for transmitting power of the first motor to thedriving shaft of the first running wheels.
 20. The powertrain accordingto claim 14, wherein a charge sustaining mode is implemented in whichpower of the engine is transmitted to the first motor through the firstpower transmission mechanism for electrical generation and power of thesecond motor is transmitted to the driving shaft of the second runningwheels through the decelerator during power transmission of the firstpower transmission mechanism for transmitting power of the engine to thefirst motor and during disengagement of transmission of power betweenthe first motor and the driving shaft of the first running wheels by thesecond power transmission mechanism.
 21. The powertrain according toclaim 14, further comprising a fourth power transmission mechanism,which is disposed between the first power transmission mechanism and thesecond power transmission mechanism so as to selectively transmit theremaining power divided from the engine to the second power transmissionmechanism, which is connected to the driving shaft of the first runningwheels, from the first power transmission mechanism.
 22. The powertrainaccording to claim 21, wherein the fourth power transmission mechanismcomprises: a third synchronizer connected to the second powertransmission shaft and transmitting power to the driving shaft of thefirst running wheels from the second power transmission mechanism; and afourth output gear connected to the second power transmission shaft viathe third synchronizer such that transmission of power between thefourth output gear and the second power transmission shaft isselectively engaged or disengaged by the third synchronizer, and whichengages with the first motor power transmission gear which transmitspower of the engine from the first power transmission mechanism.
 23. Thepowertrain according to claim 21, wherein a parallel mode is implementedin which the remaining power divided from the engine is transmitted tothe driving shaft of the first running wheels through the first powertransmission mechanism, the fourth power transmission mechanism and thesecond power transmission mechanism to be used together with power ofthe second motor to drive the vehicle during power transmission of thefirst power transmission mechanism for transmitting power of the engineto the first motor, during disengagement of transmission of powerbetween the first motor and the driving shaft of the first runningwheels by the second power transmission mechanism, and during powertransmission of the fourth power transmission mechanism.
 24. Thepowertrain according to claim 21, wherein the second power transmissionmechanism comprises: a second synchronizer connected to a rotating shaftof the first motor; a first output gear connected to the rotating shaftof the first motor via the second synchronizer such that transmission ofpower between the first output gear and the rotating shaft of the firstmotor is selectively engaged or disengaged by the second synchronizer; asecond output gear coupled to the second power transmission shaft andengaged with the first output gear; and a third output gear coupled tothe second power transmission shaft, which is coaxial with the secondoutput gear, and connected to the driving shaft of the first runningwheels in a power transmittable manner, wherein the powertrain furthercomprises a fourth synchronizer connected to the second powertransmission shaft to engage or disengage transmission of power betweenthe second output gear and the second power transmission shaft.
 25. Thepowertrain according to claim 22, wherein the second power transmissionmechanism comprises: a second synchronizer connected to a rotating shaftof the first motor; a first output gear connected to the rotating shaftof the first motor via the second synchronizer such that transmission ofpower between the first output gear and the rotating shaft of the firstmotor is selectively engaged or disengaged by the second synchronizer; asecond output gear coupled to the second power transmission shaft andengages with the first output gear; and a third output gear coupled tothe second power transmission shaft, which is coaxial with the secondoutput gear, and connected to the driving shaft of the first runningwheels in a power transmittable manner, wherein the powertrain furthercomprises a fourth synchronizer connected to the second powertransmission shaft such that transmission of power between the secondoutput gear and the second power transmission shaft is engaged ordisengaged, wherein a gear ratio of the second output gear to the firstoutput gear is different from a gear ratio of the fourth output gear tothe first motor power transmission gear.
 26. The powertrain according toclaim 24, wherein a parallel mode is implemented in which the remainingpower divided from the engine is transmitted to the driving shaft of thefirst running wheels through the first power transmission mechanism, thefourth synchronizer, and the second power transmission mechanism to beused together with power of the second motor to drive the vehicle duringpower transmission of the first power transmission mechanism fortransmitting power of the engine to the first motor, during powertransmission of the second power transmission mechanism for engagingtransmission of power between the rotating shaft of the first motor andthe driving shaft of the first running wheels, and during disengagementof power transmission of the fourth power transmission mechanism andpower transmission of the fourth synchronizer.
 27. The powertrainaccording to claim 14, wherein the first motor is operated as agenerator using power transmitted thereto.